The present invention relates to flow regulators, for regulating the flow of a fluid. The invention is particularly useful as a drip-irrigation emitter, and is therefore described below with respect to this application, but it will be appreciated that the invention could be used in other flow-regulation applications as well.
One well known type of flow regulator, particularly used for regulating the rate of water flow to a water sprinkler, sprayer or drip-irrigation emitter, includes a body member formed with an inlet opening, an outlet opening, and a groove defining a flow pathway interconnecting the two openings. Such a flow regulator further includes a flexible member, e.g., a resilient or elastic film or membrane, overlying the flow pathway so as to meter the flow there through in response to the dynamic pressure of the fluid. That is to say, one side of the resilient member is subjected to a relatively static pressure, usually the inlet pressure, and the other side (which contacts the face of the body member so as to overly the recesses through which the fluid flows) is subjected to the pressure of the fluid flowing through the recesses. The latter pressure is a dynamic one, varying with the rate of fluid flow; i.e., a higher rate of flow produces a lower pressure. Accordingly, an increase in the rate of flow through the recesses causes a reduction in the pressure applied to that face of the resilient member, and therefore the static pressure on the opposite face of the resilient member tends to move it deeper into the recess, thereby reducing its cross-sectional area and restricting the flow through it. Such regulators usually also include a stop within the flow passageway for limiting the inward displacement of the resilient member, such that the clearance between the stop and the inner face of the resilient member serves as the metering passageway for metering the flow of the fluid from the inlet to the outlet.
One drawback of such known flow regulators is that the above mentioned metering passageway is of relatively short length, so that small changes in this passageway produce relatively large changes in the flow rate. In addition, such a relatively short metering passageway is highly sensitive to clogging by foreign particles in the fluid. Further, such flow regulators are also highly sensitive to the stiffness of the flexible or resilient member because of the short metering passageway.